Problems getting the contactor to engage - http://www.hvacmechanic.com/ Forums
Original message
| Jamus
 |  "Problems getting the contactor to engage"
, posted Fri 13 Jun 01:08  
Problems getting the contactor to engage on a Nordyne Splitsystem Heatpump Model MT3BA. I'm getting the 24Vac from the Inside Thermostat coming into the Defrost Board #917178 measured from "Y" to "C" when the thermostat is calling for cooling, but nothing across the Contactor's coil which come from "T2" and "C". There are no High or Low pressure switches in the system. The Defrost Board is equipped with a 5 min anti-short delay and there is a Defrost Thermostat installed on the Condensor coils. I orginally thought the anti-short relay on the Defrost Board to be the problem because it's contacts are what connects "T1" to "T2" and it showed signs or corrosion so I ordered a new board and installed it. Still nothing. I re-installed the old board and installed a jumper between the test point "T2" and "Y". The coil energizes and the compressor along both fans run. The Indoor fan works regardless. With the jumper inplace and the thermostat calling for cooling the compressor runs and cools the mobile home. Can someone help me out with what I must be missing here? What else could cause my problems? Does anyone know how to test the Defrost Board?
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Replies:
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| TnNATE1412
| "Re(1):Problems getting the contactor to engag" , posted Fri 13 Jun 06:11
Unfortunately, I have had the same problem with NEW boards being bad (loose solder joint, etc.) There is a test procedure to bypass the time delay, but I don't have the paperwork. It should have been sent with the replacement board, unless it had been installed prior and was bad. By the way, boards for mobile home systems have to be purchased through a mobile home rep in order for Nordyne to issue warranty replacement on parts. A residential Nordyne distributor CANNOT get warranty for a mobile home unit. Go figure!
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